Binary electromagnetic event indicator

ABSTRACT

A two-state electromagnetic indicator utilizes a thin disc having discrete permanent magnetic poles. The disc, which has opposite sides of differing color, is latched to the outermost portion of the magnetic core of an electromagnet. DC current supplied to the electromagnet will cause a polarity opposite to the disc polarity, thereby causing the disc to be repelled and consequently to flip and change the indication. Means for restoring the disc to its original position are described.

United States Patent Patterson Nov. 20, 1973 BINARY ELECTROMAGNETIC EVENT INDICATOR Primary Examiner-Harold l. Pitts [75] Inventor: Willard 1. Patterson, Wolcott, Conn. Attorneyhprank Tnfan [73] Assignee: North American Philips Corporation, New York, N.Y. [57] ABSTRACT A two-state electromagnetic indicator utilizes a thin [22] Flled' 1972 disc having discrete permanent magnetic poles. The [21] Appl. No.: 241,232 disc, which has opposite sides of differing color, is latched to the outermost portion of the magnetic core [52] U S Cl 340/373 R 340/378 R of an electromagnet. DC current supplied to the electromagnet will cause a polarity opposite to the disc Gosh 15/00 polarity, thereby causing the disc to be repelled and consequently to flip and change the indication. Means [56] References Cited for restoring the disc to its original position are described. UNITED STATES PATENTS 3,s24,35s 8/1970 Dick 340 373 x 7 9 Drawing Figures PATENTEDNUVZOIW 3.714. 19 9 SHEET 1 [1F 3 l/wvy/ II ll,

PATENIED 3. 774. 1 99 sum 3 or 3 BACKGROUND OF THE INVENTION The present invention relates to indicators and, more particularly, to binary magnetic indicators having a non-illuminated contrasting color display.

Non-illuminated magnetic displays are known in the prior art. A number of examples of prior art devices employ pivoted rotatable or translatable indicating elements which are actuated by either permanent magnet or electromagnetic devices. In some cases, the pivoted devices are magnetic and are caused to move by virtue of opposing or attracting magnetic fields. This requirement for pivoting results in unnecessary bulk and complexity in such indicators. Other types of prior art magnetic indicators employ a multi-step actuation sequence to effect the required change of indication in the indicator. These types of devices are similarly excessively complex and economically expensive to manufacture. These prior approaches are also not capable of achieving substantially high speeds in changing of state of the indicator. Many of these devices are also incapable of latching or memory.

It is accordingly an object of the present invention to provide a binary indicating element which is simple in operation and economic in production.

It is another object of the invention to provide a magnetically operated binary indicator employing an indicating element which changes position without a pivoting structure.

It is a further object of the invention to provide a magnetic binary indicator which is readily adaptable to miniaturization.

It is a further object of the present invention to provide a binary magnetic element which may be employed in an array of such elements.

It is still further object of the present invention to provide a binary magnetic indicator which is actuated by a single change of state of a DC voltage.

It is still another object of the present invention to provide a binary magnetic indicator which is capable of extremely rapid changes of state.

It is yet another object of the present invention to provide a binary magnetic indicator which is capable of maintaining its changed state after the input signal has disappeared and remaining latched in that condition.

Other objects of the present invention will become apparent by reference to the following description and drawings while the scope of the invention will be pointed out in the appended claims.

SUMMARY OF THE INVENTION In accordance with the invention a binary electromagnetic indicator comprises an electromagnetic element having a ferromagnetic core and at least one coil, permanently magnetized indicating means having flat top and bottom portions and being positioned at one end of the magnetic core and magnetically coupled thereto, the indicating means having distinguishing indicia on top and bottom portions, the indicating means also for indicating one of two conditions. Also included are transparent means for covering the indicating means and for providing a limit of travel to said indicating means, and means for supplying a current to the coil to create a magnetic field in the electromagnetic element, the field being opposite to and greater than that of the indicating means, whereby the indicating means is repelled by the field of the magnetic element and, after striking the covering means, flips over and recouples to the magnetic core.

BRIEF DESCRIPTION OF THE DRAWINGS DESRIPTION OF THE PREFERRED EMBODIMENTS Referring initially to FIG. 1, shown there is electromagnetic unit 14 which has a ferro-magnetic core 20. Located and magnetically coupled or latched to one end of core 20 is a permanently magnetized indicating means 22 which has flat top and bottom portions. The indicating means ispositioned at one end of the magnetic core and magnetically coupled thereto. The indicating means, normally in the form ofa flat disc, is typically provided with binary indicia. on the flat portions thereof. The indicia are for indicating one of two conditions. Transparent means for covering the indicating means 22 is shown as plastic cover 15. Means are provided, typically current lead in wires 28, for supplying a current to the coil to create a magnetic field in the electromagntic unit.

The indicator is basically housed in a non-magnetic case 13 which as formed is open at both ends. The dase material is typically plastic and the case is generally of cylindrical shape. It is preferred that the front or top end of the case be formed with an inwardly extending flange which defines a display window (17) and acts as a shoulder to support a suitable transparent cover 15. This cover 15 preferably is constructed of plastic or glass and may contain a suitable magnifying lens 19 for assisting visibility. Supported within the case or housing 13 and engaging the transparent cover 15 is a bobbin or coil form 10. The cover is typically cemented to flange 4 or mechanically held tight against it by a bobbin 10. The bobbin which is recessed in recess 12 of case 13 may be cemented or mechanically held in place.

The electromagnetic unit 14 includes bobbin 10 which has a hollow stem 16 and carries a coil of insulated wire 18. Located in the stern of the bobbin is a magnetizable core 20. The magnetizable core is preferably made of soft iron. However, in some cases where a greater degree of latching or magnetic coupling is required, the core may be made of hardened steel. The top end of the core is generally flush with the bobbin l0 and also contacts the indicating element or magnetic disc 22. The bottom end of the core 20 is flush with the end of bobbin 10. As shown in FIG. 1, the bottom end of the bobbin is double flanged, 24 and 26. Flange 24 acts to support the coil wire while the flange 26 supports lead wire 28 or terminals which may be at tached to the magnetic indicator. Area 30 between the two bottom flanges is intended as a termination point for the coil wire 18 and the output lead wire 28. It may be desirable to retain the electromagnetic unit within the housing via a suitable insulating potting compound.

Indicator disc 22 is provided with binary indicia. In the embodiment illustrated, the indicia consists of two differing colors, one side of disc 22 is one predetermined color, and the other side a distinguishing and different color. Disc 22 is constructed as a permanent magnet having a pair of discrete poles. Typical construction material is ferrite composition with an elastimer binder. The indicating element 22 is confined to a chamber 32 by the transparent cover which is preferably dome shaped. The disc 22 is sized appreciably smaller than the cover so as to fit loosely within the chamber. This allows ample freedom of movement of the disc to enable it to flip and align itself in the magnetic field in the manner to be described below. As shown in FIG. 2, the disc 22 is more or less centrally located and latched upon the core within the cross section of the cover 15.

Referring now to FIGS. 3A G, the operation of the magnetic binary indicating element will be described.

In FIG. 3A, the normal rest position of the indicator is shown. Indicating disc 22 is seen to have two magnetic portions, north pole portion 30 and south pole portion 31. In the rest position, assuming that no current is supplied to the electromagnet, the attraction of the closest permanent pole of disc 22 to the ferromagnetic core will maintain the position of the indicating disc at the core surface. The top surface of the north pole portion of indicating disc 22 is visible through the lens 8 of the covering dome. When a change of color is desired, it is effected by applying a DC signal generated by a DC source to lead wires 28 which, in turn, excites electromagnetic unit 14. If this is done in the FIG. 3A configuration and the DC signal has a polarity and magnitude of sufficient size, it will cause the coil to produce a magnetic field opposite to and greater than that of the permanent magnetic poles of disc 22. The field is concentrated in ferro-magnetic core so that its upper end becomes (in this case) a south pole, and its lower end, a north pole. The strength of this repelling field causes the disc to move away from the core 20 as shown in FIG. 3B. The relative uniformity of the repelling field causes the disc to initially move toward the lens 8 without flipping.

FIG. 3C illustrates the magnetic disc striking the lens which acts as a stop for the disc. If the magnetic field were perfectly balanced (an impossibility in practical situations) the disc would remain pinned to the lens until the DC pulse was removed. Those familiar with trying to balance opposing magnetic forces understand that there is a tendency for one of the elements to slide off to the side. This effect occurs in the present situation. FIG. 3D illustrates this sideward movement as a result of the imbalance in the magnetic field. The disc slides off toward the weakest part of the repelling field. FIG. 3E illustrates the point where the attracting and repelling forces are approximately equal. In this position the magnetic indicating disc 22 is tilted approximately 9 from the starting position. FIGS. 3F and G illustrate the return of the indicating disc to the start position with north pole 30 now juxtaposed to the south pole 32 of the'electromagnetic core, with 31, the south pole which originally faced away from the lens, being the indicating portion which is visible through the lens 8.

Thus, the complete cycle of the magnetic indicating device has been shown. The flipped disc will remain in the position shown in FIG. 36 until the core is magnetized within an opposing field to that of the disc. This is done by either using a voltage of opposite polarity applied to lead-in conductors 28 or employing a second winding oppositely wound to the coil 18 to effect the appropriate magnetic relationship.

The construction of the present invention is signifcant in that it provides for memory." That is, if the input signal is removed, the indicator will remain in its changed state. Similarly, input signals of the same polarity cannot change the state of the indicator. Only'a signal of opposite polarity can effect a change of state. This feature can significantly simplify the logic circuitry necessary to operate the device.

It should be appreciated that the use of a large electromagnetic element and a rather small disc having small mass, creates a very high force-to-mass ratio. This enable the indicator to change state very rapidly. In practice, a switching speed in the order of 30 milliseconds has been measured, however, this is not intended as a limitation to the switching speed.

Thus, it is seen that the binary magnetic indicator, according to the present invention, is a simple, economic unit which employs no parts subject to frictional wear, and wherein the only moveable unit is the indicating element itself. The device can be made extremely small and is readily adapted to miniaturization. This type of device may be readily used in an array of such devices to effect an appropriate display of alpha/numeric type characters. The device may also be used as a simple indicating element for any parameter which has been converted to a DC electrical signal.

While the invention has been particularly shown and described with reference to the preferred embodiments thereof, it will be understood by those skilled in the art that various modifications and changes in form and detail may be made therein without departing from the true spirit and scope of the present invention.

What is claimed is:

l. A binary electromagnetic indicator comprising:

an electromagnetic element having a ferro-magnetic core and at least one coil; permanently magnetized indicating means having fiat top and bottom portions, said means being positioned at one end of the magnetic core and magnetically coupled thereto, said means having distinguishing indicia on top and bottom portions, said means also for indicating one of two conditions;

transparent means for covering said permanently magnetized means;

and means for supplying a current to said coil to create a magnetic field in said electromagnetic element, said field being opposite to and greater than that of the indicating means whereby said indicating means is repelled by the field of magnetic elements and, after striking the covering means, flips over and recouples to said magnetic coil.

2. The indicator of claim 1 wherein said indicating means is in the form of a flat disc of low mass.

3. The indicator of claim 1 wherein the indicia on top and bottom portions are in the form of differing colored surfaces.

4. The indicator of claim 1 wherein the current excitation is of DC polarity and the indicating means can be restored to the original position by reversing the DC polarity.

5. The indicator of claim 1 wherein there is additional coil of said electromagnetic element which when 3 ,7 74, 1 99 5 6 excited by DC current produces a field opposite to that eating disc surface. of a first coil which additional coil is utilized to return said indicating means to the original position.

6. The indicator of claim 1 wherein said transparent mg of most appmxlmately 30 mmlseconds means includes a lens for optically enlarging the indi 5 7. The indicator of claim 1 having a speed of switch- 

1. A binary electromagnetic indicator comprising: an electromagnetic element having a ferro-magnetic core and at least one coil; permanently magnetized indicating means having flat top and bottom portions, said means being positioned at one end of the magnetic core and magnetically coupled thereto, said means having distinguishing indicia on top and bottom portions, said means also for indicating one of two conditions; transparent means for covering said permanently magnetized means; and means for supplying a current to said coil to create a magnetic field in said electromagnetic element, said field being opposite to and greater than that of the indicating means whereby said indicating means is repelled by the field of magnetic elements and, after striking the covering means, flips over and recouples to said magnetic coil.
 2. The indicator of claim 1 wherein said indicating means is in the form of a flat disc of low mass.
 3. The indicator of claim 1 wherein the indicia on top and bottom portions are in the form of differing colored surfaces.
 4. The indicator of claim 1 wherein the current excitation is of DC polarity and the indicating means can be restored to the original position by reversing the DC polarity.
 5. The indicator of claim 1 wherein there is additional coil of said electromagnetic element which when excited by DC current produces a field opposite to that of a first coil which additional coil is utilized to return said indicating means to the original position.
 6. The indicator of claim 1 wherein said transparent means includes a lens for optically enlarging the indicating disc surface.
 7. The indicator of claim 1 having a speed of switching of at most approximately 30 milliseconds. 